PCS 125 Lecture Notes - Lecture 18: 30 Foot Fall, Logarithmic Scale
Document Summary
The range of intensities detectible by the human ear is very large. It is convenient to use a logarithmic scale to determine the intensity level, b. It is taken to be the threshold of hearing. What is the sound level that corresponds to an intensity of 2. 0 x. = 10 log (2. 0 x 10-7 w/m2 / 1. 0 x 10-12 w/m2) = 10 log 2. 0 x 105 = 53 db rule of thumb: a doubling in the loudness is approximately equivalent to an increase of 10 db. Sound level in decibels relates to a physical measurement of the strength of a sound. We can also describe a psychological measurement of the strength of a sound. Our bodies calibrate a sound by comparing it to a reference sound. There is a complex relationship between loudness and frequency. The white area shows average human response to sound. The lower curve of the white area shows the threshold of hearing.
